The soccer life of San Jose Earthquakes forward Cornell Glen has always been about walking a tightrope, but perhaps never more so than right now.

The 29-year-old Glen has earned 59 career caps with the Trinidad and Tobago National Team – and 35 MLS goals in 69 league appearances – by hanging on the shoulder of the opposition’s final defender, navigating the fine line between an offside call and a breakaway for a one-on-one against the keeper.

But ever since he joined San Jose prior to last season, Glen’s health has also been an issue, with nagging muscle injuries often making his availability a week-to-week proposition.

After replacing ineffective striker Ryan Johnson in the starting lineup, Glen showed why he has averaged a goal every 95 minutes of play in his MLS career. He tallied three matches ago against Philadelphia and, in San Jose’s match last month against league-leading Los Angeles, Glen made the run that ignited the sequence that led to the Quakes’ first goal.

Even so, San Jose coach Frank Yallop is loath to overuse him, wary of incurring another injury.

“We want to get him fitter, so he doesn’t get injured, but we don’t want to push him too much to get injured,” Yallop said. “That’s the big issue. It’s a tough one.”

Glen, who missed several weeks with a hamstring injury earlier this season, is currently nursing what he terms a “slight” groin strain. In order to save him for this past weekend, in which Glen started in a 1-0 home loss to Seattle, the team held him out of practice last Tuesday, giving him drills meant to keep in shape without aggravating the pain.

“I’m probably 90 percent,” Glen said. “[The groin injury] is sore, but otherwise I’m doing OK. It’s a matter of getting game time, match time and match fitness. Once I’m match fit, I think I can always perform well and help the team as best as I can. It’s a matter of getting time in, week-in and week-out, and getting the body used to it.”

Glen drives some fans nuts with his propensity to get whistled for being offside, but that’s part of the cost of business in using him, since courting that risk is necessary for him to be most effective.

“He unbalances defenses,” Yallop said. “I think he’s done a nice job of running the line and being dangerous. He’s always trying to get a breakaway. And he adds a different dimension to our team. It doesn’t always equate to us winning, but it gives us a different look.”

On offense, Glen fits in just fine with Yallop’s counterattacking plan for this roster. But hounding the opposition with terrier-like tenacity is – another prized Yallop trait among forwards – is not exactly Glen’s game.

“If it’s working for us, it’s probably the best thing that we play that way, and play on the counterattack,” Glen said. “So far, it’s not going too bad, but it’s not going too well, either. There’s a lot of stuff we’ve got to work on.”

Geoff Lepper covers the Earthquakes for MLSsoccer.com. He can be reached at sanjosequakes@gmail.com. On Twitter: @sjquakes.